| 1 | @c This is part of the Emacs manual. |
| 2 | @c Copyright (C) 2004-2014 Free Software Foundation, Inc. |
| 3 | @c See file emacs.texi for copying conditions. |
| 4 | @c |
| 5 | @c This file is included either in emacs-xtra.texi (when producing the |
| 6 | @c printed version) or in the main Emacs manual (for the on-line version). |
| 7 | @node Fortran |
| 8 | @section Fortran Mode |
| 9 | @cindex Fortran mode |
| 10 | @cindex mode, Fortran |
| 11 | |
| 12 | @cindex Fortran fixed form and free form |
| 13 | @cindex Fortran 77 and Fortran 90, 95, 2003, 2008 |
| 14 | @findex f90-mode |
| 15 | @findex fortran-mode |
| 16 | Fortran mode is meant for editing ``fixed form'' (and also ``tab |
| 17 | format'') source code (normally Fortran 77). For editing more modern |
| 18 | ``free form'' source code (Fortran 90, 95, 2003, 2008), use F90 mode |
| 19 | (@code{f90-mode}). Emacs normally uses Fortran mode for files with |
| 20 | extension @samp{.f}, @samp{.F} or @samp{.for}, and F90 mode for the |
| 21 | extensions @samp{.f90}, @samp{.f95}, @samp{.f03} and @samp{.f08}. |
| 22 | Customize @code{auto-mode-alist} to add more extensions. GNU Fortran |
| 23 | supports both free and fixed form. This manual mainly documents Fortran |
| 24 | mode, but the corresponding F90 mode features are mentioned when |
| 25 | relevant. |
| 26 | |
| 27 | Fortran mode provides special motion commands for Fortran statements |
| 28 | and subprograms, and indentation commands that understand Fortran |
| 29 | conventions of nesting, line numbers and continuation statements. |
| 30 | Fortran mode has support for Auto Fill mode that breaks long lines into |
| 31 | proper Fortran continuation lines. Fortran mode also supports Hideshow |
| 32 | minor mode |
| 33 | @iftex |
| 34 | (@pxref{Hideshow,,, emacs, the Emacs Manual}), |
| 35 | @end iftex |
| 36 | @ifnottex |
| 37 | (@pxref{Hideshow}), |
| 38 | @end ifnottex |
| 39 | and Imenu |
| 40 | @iftex |
| 41 | (@pxref{Imenu,,, emacs, the Emacs Manual}). |
| 42 | @end iftex |
| 43 | @ifnottex |
| 44 | (@pxref{Imenu}). |
| 45 | @end ifnottex |
| 46 | |
| 47 | Special commands for comments are provided because Fortran comments |
| 48 | are unlike those of other languages. Built-in abbrevs optionally save |
| 49 | typing when you insert Fortran keywords. |
| 50 | |
| 51 | Use @kbd{M-x fortran-mode} to switch to this major mode. This |
| 52 | command runs the hook @code{fortran-mode-hook}. |
| 53 | @iftex |
| 54 | @xref{Hooks,,, emacs, the Emacs Manual}. |
| 55 | @end iftex |
| 56 | @ifnottex |
| 57 | @xref{Hooks}. |
| 58 | @end ifnottex |
| 59 | |
| 60 | @menu |
| 61 | * Motion: Fortran Motion. Moving point by statements or subprograms. |
| 62 | * Indent: Fortran Indent. Indentation commands for Fortran. |
| 63 | * Comments: Fortran Comments. Inserting and aligning comments. |
| 64 | * Autofill: Fortran Autofill. Auto fill support for Fortran. |
| 65 | * Columns: Fortran Columns. Measuring columns for valid Fortran. |
| 66 | * Abbrev: Fortran Abbrev. Built-in abbrevs for Fortran keywords. |
| 67 | @end menu |
| 68 | |
| 69 | @node Fortran Motion |
| 70 | @subsection Motion Commands |
| 71 | |
| 72 | In addition to the normal commands for moving by and operating on |
| 73 | ``defuns'' (Fortran subprograms---functions and subroutines, as well |
| 74 | as modules for F90 mode, using the commands @code{fortran-end-of-subprogram} |
| 75 | and @code{fortran-beginning-of-subprogram}), Fortran mode provides |
| 76 | special commands to move by statements and other program units. |
| 77 | |
| 78 | @table @kbd |
| 79 | @kindex C-c C-n @r{(Fortran mode)} |
| 80 | @findex fortran-next-statement |
| 81 | @findex f90-next-statement |
| 82 | @item C-c C-n |
| 83 | Move to the beginning of the next statement |
| 84 | (@code{fortran-next-statement}/@code{f90-next-statement}). |
| 85 | |
| 86 | @kindex C-c C-p @r{(Fortran mode)} |
| 87 | @findex fortran-previous-statement |
| 88 | @findex f90-previous-statement |
| 89 | @item C-c C-p |
| 90 | Move to the beginning of the previous statement |
| 91 | (@code{fortran-previous-statement}/@code{f90-previous-statement}). |
| 92 | If there is no previous statement (i.e., if called from the first |
| 93 | statement in the buffer), move to the start of the buffer. |
| 94 | |
| 95 | @kindex C-c C-e @r{(F90 mode)} |
| 96 | @findex f90-next-block |
| 97 | @item C-c C-e |
| 98 | Move point forward to the start of the next code block, or the end of |
| 99 | the current one, whichever comes first (@code{f90-next-block}). |
| 100 | A code block is a subroutine, @code{if}--@code{endif} statement, and |
| 101 | so forth. This command exists for F90 mode only, not Fortran mode. |
| 102 | With a numeric argument, it moves forward that many blocks. |
| 103 | |
| 104 | @kindex C-c C-a @r{(F90 mode)} |
| 105 | @findex f90-previous-block |
| 106 | @item C-c C-a |
| 107 | Move point backward to the previous block |
| 108 | (@code{f90-previous-block}). This is like @code{f90-next-block}, but |
| 109 | moves backwards. |
| 110 | |
| 111 | @kindex C-M-n @r{(Fortran mode)} |
| 112 | @findex fortran-end-of-block |
| 113 | @findex f90-end-of-block |
| 114 | @item C-M-n |
| 115 | Move to the end of the current code block |
| 116 | (@code{fortran-end-of-block}/@code{f90-end-of-block}). With a numeric |
| 117 | argument, move forward that number of blocks. The mark is set before |
| 118 | moving point. The F90 mode version of this command checks for |
| 119 | consistency of block types and labels (if present), but it does not |
| 120 | check the outermost block since that may be incomplete. |
| 121 | |
| 122 | @kindex C-M-p @r{(Fortran mode)} |
| 123 | @findex fortran-beginning-of-block |
| 124 | @findex f90-beginning-of-block |
| 125 | @item C-M-p |
| 126 | Move to the start of the current code block |
| 127 | (@code{fortran-beginning-of-block}/@code{f90-beginning-of-block}). This |
| 128 | is like @code{fortran-end-of-block}, but moves backwards. |
| 129 | @end table |
| 130 | |
| 131 | The commands @code{fortran-beginning-of-subprogram} and |
| 132 | @code{fortran-end-of-subprogram} move to the start or end of the |
| 133 | current subprogram, respectively. The commands @code{fortran-mark-do} |
| 134 | and @code{fortran-mark-if} mark the end of the current @code{do} or |
| 135 | @code{if} block, and move point to the start. |
| 136 | |
| 137 | |
| 138 | @node Fortran Indent |
| 139 | @subsection Fortran Indentation |
| 140 | |
| 141 | Special commands and features are needed for indenting fixed (or tab) |
| 142 | form Fortran code in order to make sure various syntactic entities (line |
| 143 | numbers, comment line indicators and continuation line flags) appear in |
| 144 | the required columns. |
| 145 | |
| 146 | @menu |
| 147 | * Commands: ForIndent Commands. Commands for indenting and filling Fortran. |
| 148 | * Contline: ForIndent Cont. How continuation lines indent. |
| 149 | * Numbers: ForIndent Num. How line numbers auto-indent. |
| 150 | * Conv: ForIndent Conv. Conventions you must obey to avoid trouble. |
| 151 | * Vars: ForIndent Vars. Variables controlling Fortran indent style. |
| 152 | @end menu |
| 153 | |
| 154 | @node ForIndent Commands |
| 155 | @subsubsection Fortran Indentation and Filling Commands |
| 156 | |
| 157 | @table @kbd |
| 158 | @item C-M-j |
| 159 | Break the current line at point and set up a continuation line |
| 160 | (@code{fortran-split-line}). |
| 161 | @item M-^ |
| 162 | Join this line to the previous line (@code{fortran-join-line}). |
| 163 | @item C-M-q |
| 164 | Indent all the lines of the subprogram that point is in |
| 165 | (@code{fortran-indent-subprogram}). |
| 166 | @item M-q |
| 167 | Fill a comment block or statement (using @code{fortran-fill-paragraph} |
| 168 | or @code{fortran-fill-statement}). |
| 169 | @end table |
| 170 | |
| 171 | @kindex C-M-q @r{(Fortran mode)} |
| 172 | @findex fortran-indent-subprogram |
| 173 | The key @kbd{C-M-q} runs @code{fortran-indent-subprogram}, a command |
| 174 | to reindent all the lines of the Fortran subprogram (function or |
| 175 | subroutine) containing point. |
| 176 | |
| 177 | @kindex C-M-j @r{(Fortran mode)} |
| 178 | @findex fortran-split-line |
| 179 | The key @kbd{C-M-j} runs @code{fortran-split-line}, which splits |
| 180 | a line in the appropriate fashion for Fortran. In a non-comment line, |
| 181 | the second half becomes a continuation line and is indented |
| 182 | accordingly. In a comment line, both halves become separate comment |
| 183 | lines. |
| 184 | |
| 185 | @kindex M-^ @r{(Fortran mode)} |
| 186 | @kindex C-c C-d @r{(Fortran mode)} |
| 187 | @findex fortran-join-line |
| 188 | @kbd{M-^} or @kbd{C-c C-d} runs the command @code{fortran-join-line}, |
| 189 | which joins a continuation line back to the previous line, roughly as |
| 190 | the inverse of @code{fortran-split-line}. The point must be on a |
| 191 | continuation line when this command is invoked. |
| 192 | |
| 193 | @kindex M-q @r{(Fortran mode)} |
| 194 | @kbd{M-q} in Fortran mode fills the comment block or statement that |
| 195 | point is in. This removes any excess statement continuations. |
| 196 | |
| 197 | @node ForIndent Cont |
| 198 | @subsubsection Continuation Lines |
| 199 | @cindex Fortran continuation lines |
| 200 | |
| 201 | @vindex fortran-continuation-string |
| 202 | Most Fortran 77 compilers allow two ways of writing continuation lines. |
| 203 | If the first non-space character on a line is in column 5, then that |
| 204 | line is a continuation of the previous line. We call this @dfn{fixed |
| 205 | form}. (In GNU Emacs we always count columns from 0; but note that |
| 206 | the Fortran standard counts from 1.) The variable |
| 207 | @code{fortran-continuation-string} specifies what character to put in |
| 208 | column 5. A line that starts with a tab character followed by any digit |
| 209 | except @samp{0} is also a continuation line. We call this style of |
| 210 | continuation @dfn{tab format}. (Fortran 90 introduced ``free form'', |
| 211 | with another style of continuation lines). |
| 212 | |
| 213 | @vindex indent-tabs-mode @r{(Fortran mode)} |
| 214 | @vindex fortran-analyze-depth |
| 215 | @vindex fortran-tab-mode-default |
| 216 | Fortran mode can use either style of continuation line. When you |
| 217 | enter Fortran mode, it tries to deduce the proper continuation style |
| 218 | automatically from the buffer contents. It does this by scanning up to |
| 219 | @code{fortran-analyze-depth} (default 100) lines from the start of the |
| 220 | buffer. The first line that begins with either a tab character or six |
| 221 | spaces determines the choice. If the scan fails (for example, if the |
| 222 | buffer is new and therefore empty), the value of |
| 223 | @code{fortran-tab-mode-default} (@code{nil} for fixed form, and |
| 224 | non-@code{nil} for tab format) is used. @samp{/t} |
| 225 | (@code{fortran-tab-mode-string}) in the mode line indicates tab format |
| 226 | is selected. Fortran mode sets the value of @code{indent-tabs-mode} |
| 227 | accordingly. |
| 228 | |
| 229 | If the text on a line starts with the Fortran continuation marker |
| 230 | @samp{$}, or if it begins with any non-whitespace character in column |
| 231 | 5, Fortran mode treats it as a continuation line. When you indent a |
| 232 | continuation line with @key{TAB}, it converts the line to the current |
| 233 | continuation style. When you split a Fortran statement with |
| 234 | @kbd{C-M-j}, the continuation marker on the newline is created according |
| 235 | to the continuation style. |
| 236 | |
| 237 | The setting of continuation style affects several other aspects of |
| 238 | editing in Fortran mode. In fixed form mode, the minimum column |
| 239 | number for the body of a statement is 6. Lines inside of Fortran |
| 240 | blocks that are indented to larger column numbers must use only the |
| 241 | space character for whitespace. In tab format mode, the minimum |
| 242 | column number for the statement body is 8, and the whitespace before |
| 243 | column 8 must consist of one tab character. |
| 244 | |
| 245 | @node ForIndent Num |
| 246 | @subsubsection Line Numbers |
| 247 | |
| 248 | If a number is the first non-whitespace in the line, Fortran |
| 249 | indentation assumes it is a line number and moves it to columns 0 |
| 250 | through 4. (Columns always count from 0 in Emacs.) |
| 251 | |
| 252 | @vindex fortran-line-number-indent |
| 253 | Line numbers of four digits or less are normally indented one space. |
| 254 | The variable @code{fortran-line-number-indent} controls this; it |
| 255 | specifies the maximum indentation a line number can have. The default |
| 256 | value of the variable is 1. Fortran mode tries to prevent line number |
| 257 | digits passing column 4, reducing the indentation below the specified |
| 258 | maximum if necessary. If @code{fortran-line-number-indent} has the |
| 259 | value 5, line numbers are right-justified to end in column 4. |
| 260 | |
| 261 | @vindex fortran-electric-line-number |
| 262 | Simply inserting a line number is enough to indent it according to |
| 263 | these rules. As each digit is inserted, the indentation is recomputed. |
| 264 | To turn off this feature, set the variable |
| 265 | @code{fortran-electric-line-number} to @code{nil}. |
| 266 | |
| 267 | |
| 268 | @node ForIndent Conv |
| 269 | @subsubsection Syntactic Conventions |
| 270 | |
| 271 | Fortran mode assumes that you follow certain conventions that simplify |
| 272 | the task of understanding a Fortran program well enough to indent it |
| 273 | properly: |
| 274 | |
| 275 | @itemize @bullet |
| 276 | @item |
| 277 | Two nested @samp{do} loops never share a @samp{continue} statement. |
| 278 | |
| 279 | @item |
| 280 | Fortran keywords such as @samp{if}, @samp{else}, @samp{then}, @samp{do} |
| 281 | and others are written without embedded whitespace or line breaks. |
| 282 | |
| 283 | Fortran compilers generally ignore whitespace outside of string |
| 284 | constants, but Fortran mode does not recognize these keywords if they |
| 285 | are not contiguous. Constructs such as @samp{else if} or @samp{end do} |
| 286 | are acceptable, but the second word should be on the same line as the |
| 287 | first and not on a continuation line. |
| 288 | @end itemize |
| 289 | |
| 290 | @noindent |
| 291 | If you fail to follow these conventions, the indentation commands may |
| 292 | indent some lines unaesthetically. However, a correct Fortran program |
| 293 | retains its meaning when reindented even if the conventions are not |
| 294 | followed. |
| 295 | |
| 296 | @node ForIndent Vars |
| 297 | @subsubsection Variables for Fortran Indentation |
| 298 | |
| 299 | @vindex fortran-do-indent |
| 300 | @vindex fortran-if-indent |
| 301 | @vindex fortran-structure-indent |
| 302 | @vindex fortran-continuation-indent |
| 303 | @vindex fortran-check-all-num@dots{} |
| 304 | @vindex fortran-minimum-statement-indent@dots{} |
| 305 | Several additional variables control how Fortran indentation works: |
| 306 | |
| 307 | @table @code |
| 308 | @item fortran-do-indent |
| 309 | Extra indentation within each level of @samp{do} statement (default 3). |
| 310 | |
| 311 | @item fortran-if-indent |
| 312 | Extra indentation within each level of @samp{if}, @samp{select case}, or |
| 313 | @samp{where} statements (default 3). |
| 314 | |
| 315 | @item fortran-structure-indent |
| 316 | Extra indentation within each level of @samp{structure}, @samp{union}, |
| 317 | @samp{map}, or @samp{interface} statements (default 3). |
| 318 | |
| 319 | @item fortran-continuation-indent |
| 320 | Extra indentation for bodies of continuation lines (default 5). |
| 321 | |
| 322 | @item fortran-check-all-num-for-matching-do |
| 323 | In Fortran 77, a numbered @samp{do} statement is ended by any statement |
| 324 | with a matching line number. It is common (but not compulsory) to use a |
| 325 | @samp{continue} statement for this purpose. If this variable has a |
| 326 | non-@code{nil} value, indenting any numbered statement must check for a |
| 327 | @samp{do} that ends there. If you always end @samp{do} statements with |
| 328 | a @samp{continue} line (or if you use the more modern @samp{enddo}), |
| 329 | then you can speed up indentation by setting this variable to |
| 330 | @code{nil} (the default). |
| 331 | |
| 332 | @item fortran-blink-matching-if |
| 333 | If this is @code{t}, indenting an @samp{endif} (or @samp{enddo} |
| 334 | statement moves the cursor momentarily to the matching @samp{if} (or |
| 335 | @samp{do}) statement to show where it is. The default is @code{nil}. |
| 336 | |
| 337 | @item fortran-minimum-statement-indent-fixed |
| 338 | Minimum indentation for Fortran statements when using fixed form |
| 339 | continuation line style. Statement bodies are never indented by less than |
| 340 | this. The default is 6. |
| 341 | |
| 342 | @item fortran-minimum-statement-indent-tab |
| 343 | Minimum indentation for Fortran statements for tab format continuation line |
| 344 | style. Statement bodies are never indented by less than this. The |
| 345 | default is 8. |
| 346 | @end table |
| 347 | |
| 348 | The following section describes the variables controlling the |
| 349 | indentation of comments. |
| 350 | |
| 351 | @node Fortran Comments |
| 352 | @subsection Fortran Comments |
| 353 | |
| 354 | The usual Emacs comment commands assume that a comment can follow a |
| 355 | line of code. In Fortran 77, the standard comment syntax requires an |
| 356 | entire line to be just a comment. Therefore, Fortran mode replaces the |
| 357 | standard Emacs comment commands and defines some new variables. |
| 358 | |
| 359 | @vindex fortran-comment-line-start |
| 360 | Fortran mode can also handle the Fortran 90 comment syntax where |
| 361 | comments start with @samp{!} and can follow other text. Because only |
| 362 | some Fortran 77 compilers accept this syntax, Fortran mode will not |
| 363 | insert such comments unless you have said in advance to do so. To do |
| 364 | this, set the variable @code{fortran-comment-line-start} to @samp{"!"}. |
| 365 | If you use an unusual value, you may need to change |
| 366 | @code{fortran-comment-line-start-skip}. |
| 367 | |
| 368 | |
| 369 | @table @kbd |
| 370 | @item M-; |
| 371 | Align comment or insert new comment (@code{comment-dwim}). |
| 372 | |
| 373 | @item C-x ; |
| 374 | Applies to nonstandard @samp{!} comments only (@code{comment-set-column}). |
| 375 | |
| 376 | @item C-c ; |
| 377 | Turn all lines of the region into comments, or (with argument) turn them back |
| 378 | into real code (@code{fortran-comment-region}). |
| 379 | @end table |
| 380 | |
| 381 | @kbd{M-;} in Fortran mode runs the standard @code{comment-dwim}. |
| 382 | This recognizes any kind of existing comment and aligns its text |
| 383 | appropriately; if there is no existing comment, a comment is inserted |
| 384 | and aligned. Inserting and aligning comments are not the same in |
| 385 | Fortran mode as in other modes. |
| 386 | |
| 387 | When a new comment must be inserted, if the current line is blank, a |
| 388 | full-line comment is inserted. On a non-blank line, a nonstandard @samp{!} |
| 389 | comment is inserted if you have said you want to use them. Otherwise a |
| 390 | full-line comment is inserted on a new line before the current line. |
| 391 | |
| 392 | Nonstandard @samp{!} comments are aligned like comments in other |
| 393 | languages, but full-line comments are different. In a standard full-line |
| 394 | comment, the comment delimiter itself must always appear in column zero. |
| 395 | What can be aligned is the text within the comment. You can choose from |
| 396 | three styles of alignment by setting the variable |
| 397 | @code{fortran-comment-indent-style} to one of these values: |
| 398 | |
| 399 | @vindex fortran-comment-indent-style |
| 400 | @vindex fortran-comment-line-extra-indent |
| 401 | @table @code |
| 402 | @item fixed |
| 403 | Align the text at a fixed column, which is the sum of |
| 404 | @code{fortran-comment-line-extra-indent} and the minimum statement |
| 405 | indentation. This is the default. |
| 406 | |
| 407 | The minimum indentation is |
| 408 | @code{fortran-minimum-statement-indent-tab} for tab format |
| 409 | continuation line style and @code{fortran-minimum-statement-indent-fixed} |
| 410 | for fixed form style. |
| 411 | |
| 412 | @item relative |
| 413 | Align the text as if it were a line of code, but with an additional |
| 414 | @code{fortran-comment-line-extra-indent} columns of indentation. |
| 415 | |
| 416 | @item nil |
| 417 | Don't move text in full-line comments automatically. |
| 418 | @end table |
| 419 | |
| 420 | @vindex fortran-comment-indent-char |
| 421 | In addition, you can specify the character to be used to indent within |
| 422 | full-line comments by setting the variable |
| 423 | @code{fortran-comment-indent-char} to the single-character string you want |
| 424 | to use. |
| 425 | |
| 426 | @vindex fortran-directive-re |
| 427 | Compiler directive lines, or preprocessor lines, have much the same |
| 428 | appearance as comment lines. It is important, though, that such lines |
| 429 | never be indented at all, no matter what the value of |
| 430 | @code{fortran-comment-indent-style}. The variable |
| 431 | @code{fortran-directive-re} is a regular expression that specifies which |
| 432 | lines are directives. Matching lines are never indented, and receive |
| 433 | distinctive font-locking. |
| 434 | |
| 435 | The normal Emacs comment command @kbd{C-x ;} (@code{comment-set-column}) |
| 436 | has not been redefined. If you use @samp{!} comments, this command |
| 437 | can be used with them. Otherwise it is useless in Fortran mode. |
| 438 | |
| 439 | @kindex C-c ; @r{(Fortran mode)} |
| 440 | @findex fortran-comment-region |
| 441 | @vindex fortran-comment-region |
| 442 | The command @kbd{C-c ;} (@code{fortran-comment-region}) turns all the |
| 443 | lines of the region into comments by inserting the string @samp{c$$$} at |
| 444 | the front of each one. With a numeric argument, it turns the region |
| 445 | back into live code by deleting @samp{c$$$} from the front of each line |
| 446 | in it. The string used for these comments can be controlled by setting |
| 447 | the variable @code{fortran-comment-region}. Note that here we have an |
| 448 | example of a command and a variable with the same name; these two uses |
| 449 | of the name never conflict because in Lisp and in Emacs it is always |
| 450 | clear from the context which one is meant. |
| 451 | |
| 452 | @node Fortran Autofill |
| 453 | @subsection Auto Fill in Fortran Mode |
| 454 | |
| 455 | Fortran mode has specialized support for Auto Fill mode, which is a |
| 456 | minor mode that automatically splits statements as you insert them |
| 457 | when they become too wide. Splitting a statement involves making |
| 458 | continuation lines using @code{fortran-continuation-string} |
| 459 | (@pxref{ForIndent Cont}). This splitting happens when you type |
| 460 | @key{SPC}, @key{RET}, or @key{TAB}, and also in the Fortran |
| 461 | indentation commands. You activate Auto Fill in Fortran mode in the |
| 462 | normal way. |
| 463 | @iftex |
| 464 | @xref{Auto Fill,,, emacs, the Emacs Manual}. |
| 465 | @end iftex |
| 466 | @ifnottex |
| 467 | @xref{Auto Fill}. |
| 468 | @end ifnottex |
| 469 | |
| 470 | @vindex fortran-break-before-delimiters |
| 471 | Auto Fill breaks lines at spaces or delimiters when the lines get |
| 472 | longer than the desired width (the value of @code{fill-column}). The |
| 473 | delimiters (besides whitespace) that Auto Fill can break at are |
| 474 | @samp{+}, @samp{-}, @samp{/}, @samp{*}, @samp{=}, @samp{<}, @samp{>}, |
| 475 | and @samp{,}. The line break comes after the delimiter if the |
| 476 | variable @code{fortran-break-before-delimiters} is @code{nil}. |
| 477 | Otherwise (and by default), the break comes before the delimiter. |
| 478 | |
| 479 | To enable Auto Fill in all Fortran buffers, add |
| 480 | @code{auto-fill-mode} to @code{fortran-mode-hook}. |
| 481 | @iftex |
| 482 | @xref{Hooks,,, emacs, the Emacs Manual}. |
| 483 | @end iftex |
| 484 | @ifnottex |
| 485 | @xref{Hooks}. |
| 486 | @end ifnottex |
| 487 | |
| 488 | @node Fortran Columns |
| 489 | @subsection Checking Columns in Fortran |
| 490 | |
| 491 | @vindex fortran-line-length |
| 492 | In standard Fortran 77, anything beyond column 72 is ignored. |
| 493 | Most compilers provide an option to change this (for example, |
| 494 | @samp{-ffixed-line-length-N} in gfortran). Customize the variable |
| 495 | @code{fortran-line-length} to change the line length in Fortran mode. |
| 496 | Anything beyond this point is font-locked as a comment. (Unless it is |
| 497 | inside a string: strings that extend beyond @code{fortran-line-length} |
| 498 | will confuse font-lock.) |
| 499 | |
| 500 | @table @kbd |
| 501 | @item C-c C-r |
| 502 | Display a ``column ruler'' momentarily above the current line |
| 503 | (@code{fortran-column-ruler}). |
| 504 | @item C-c C-w |
| 505 | Split the current window horizontally temporarily so that it is |
| 506 | @code{fortran-line-length} columns wide |
| 507 | (@code{fortran-window-create-momentarily}). This may help you avoid |
| 508 | making lines longer than the limit imposed by your Fortran compiler. |
| 509 | @item C-u C-c C-w |
| 510 | Split the current window horizontally so that it is |
| 511 | @code{fortran-line-length} columns wide (@code{fortran-window-create}). |
| 512 | You can then continue editing. |
| 513 | @item M-x fortran-strip-sequence-nos |
| 514 | Delete all text in column @code{fortran-line-length} and beyond. |
| 515 | @end table |
| 516 | |
| 517 | @kindex C-c C-r @r{(Fortran mode)} |
| 518 | @findex fortran-column-ruler |
| 519 | The command @kbd{C-c C-r} (@code{fortran-column-ruler}) shows a column |
| 520 | ruler momentarily above the current line. The comment ruler is two lines |
| 521 | of text that show you the locations of columns with special significance in |
| 522 | Fortran programs. Square brackets show the limits of the columns for line |
| 523 | numbers, and curly brackets show the limits of the columns for the |
| 524 | statement body. Column numbers appear above them. |
| 525 | |
| 526 | Note that the column numbers count from zero, as always in GNU Emacs. |
| 527 | As a result, the numbers may be one less than those you are familiar |
| 528 | with; but the positions they indicate in the line are standard for |
| 529 | Fortran. |
| 530 | |
| 531 | @vindex fortran-column-ruler-fixed |
| 532 | @vindex fortran-column-ruler-tabs |
| 533 | The text used to display the column ruler depends on the value of the |
| 534 | variable @code{indent-tabs-mode}. If @code{indent-tabs-mode} is |
| 535 | @code{nil}, then the value of the variable |
| 536 | @code{fortran-column-ruler-fixed} is used as the column ruler. |
| 537 | Otherwise, the value of the variable @code{fortran-column-ruler-tab} is |
| 538 | displayed. By changing these variables, you can change the column ruler |
| 539 | display. |
| 540 | |
| 541 | @kindex C-c C-w @r{(Fortran mode)} |
| 542 | @findex fortran-window-create-momentarily |
| 543 | @kbd{C-c C-w} (@code{fortran-window-create-momentarily}) temporarily |
| 544 | splits the current window horizontally, making a window |
| 545 | @code{fortran-line-length} columns wide, so you can see any lines that |
| 546 | are too long. Type a space to restore the normal width. |
| 547 | |
| 548 | @kindex C-u C-c C-w @r{(Fortran mode)} |
| 549 | @findex fortran-window-create |
| 550 | You can also split the window horizontally and continue editing with |
| 551 | the split in place. To do this, use @kbd{C-u C-c C-w} (@code{M-x |
| 552 | fortran-window-create}). By editing in this window you can |
| 553 | immediately see when you make a line too wide to be correct Fortran. |
| 554 | |
| 555 | @findex fortran-strip-sequence-nos |
| 556 | The command @kbd{M-x fortran-strip-sequence-nos} deletes all text in |
| 557 | column @code{fortran-line-length} and beyond, on all lines in the |
| 558 | current buffer. This is the easiest way to get rid of old sequence |
| 559 | numbers. |
| 560 | |
| 561 | @node Fortran Abbrev |
| 562 | @subsection Fortran Keyword Abbrevs |
| 563 | |
| 564 | Fortran mode provides many built-in abbrevs for common keywords and |
| 565 | declarations. These are the same sort of abbrev that you can define |
| 566 | yourself. To use them, you must turn on Abbrev mode. |
| 567 | @iftex |
| 568 | @xref{Abbrevs,,, emacs, the Emacs Manual}. |
| 569 | @end iftex |
| 570 | @ifnottex |
| 571 | @xref{Abbrevs}. |
| 572 | @end ifnottex |
| 573 | |
| 574 | The built-in abbrevs are unusual in one way: they all start with a |
| 575 | semicolon. For example, one built-in Fortran abbrev is @samp{;c} for |
| 576 | @samp{continue}. If you insert @samp{;c} and then insert a punctuation |
| 577 | character such as a space or a newline, the @samp{;c} expands automatically |
| 578 | to @samp{continue}, provided Abbrev mode is enabled. |
| 579 | |
| 580 | Type @samp{;?} or @samp{;C-h} to display a list of all the built-in |
| 581 | Fortran abbrevs and what they stand for. |